A nutritional fortifier for the first-feeding feed of larvae and juveniles of fish and its application

Abstract

The present invention belongs to the field of aquatic feeds, and particularly relates to a nutritional fortifier for larval and juvenile fish starter feeds and its application. The nutritional fortifier includes: eicosapentaenoic acid, docosahexaenoic acid, arachidonic acid, a compound enzyme preparation, as well as vitamin C, lecithin, taurine, and lysine. In view of the characteristics of larval and juvenile fish, such as small body size, weak motility, poor ability to adapt to the external environment, and incomplete development of the digestive system, the present invention provides a nutritional fortifier and its application that can promote the feeding of larval and juvenile fish and significantly improve the growth and survival rate of larval and juvenile fish.

Description

Technical Field

[0001] The present invention belongs to the field of aquatic feeds, and particularly relates to a nutritional fortifier for larval and juvenile fish starter feeds and its application. Background Art

[0002] Aquatic fry are the most active and important production factors in the aquaculture industry. The larval and juvenile stages of fry, as special stages in the life history of fish, have significant differences in external morphology, internal structure, and physiological metabolism methods compared with juvenile and adult fish. After hatching, larval and juvenile fish still have a yolk sac and first carry out endogenous nutrition. As they grow and develop, the yolk sac disappears and they begin to enter the exogenous nutrition stage, that is, the so-called opening period. The nutrition supplied after entering the opening period directly affects the growth and health of larval and juvenile fish.

[0003] So far, in the breeding production of cultured fish, the opening of larval and juvenile fish mainly relies on biological feeds, including artemia, rotifers, tubifex worms, etc. However, with the development of production, traditional biological feeds used in breeding production are greatly restricted in breeding production due to their high production costs, unstable yields and qualities, and possible carrying of pathogenic microorganisms. Therefore, since the 1980s, people have begun to research and develop artificial compound feeds suitable for the ingestion and digestion of aquatic fry, in order to partially or completely replace biological feeds. So far, some encouraging research results have been obtained and commercial production has been carried out.

[0004] However, larval and juvenile fish are small in size, weak in activity ability, poor in adapting to the external environment, have underdeveloped digestive systems, insufficient or lack of digestive enzyme secretion, and the nutritional composition required is very different from that of juvenile and adult fish stages, making the research and development of artificial compound feeds in the opening stage extremely difficult. In the breeding period of most cultured fish, the artificial compound feeds in the opening stage are not precisely designed according to the nutritional requirements and digestion and absorption characteristics of the seedling stage, resulting in indigestion and weakened stress resistance of the fry, which not only affects the survival rate, but even affects the subsequent cultivation stage. Therefore, although significant achievements have been made in the development of seedling-stage pellet feeds, biological feeds are still the first choice for the cultivation of larvae of aquaculture animals, which is not conducive to large-scale and controllable farming.

[0005] Feed additives are one of the important raw materials used in the modern feed industry. Although their usage in feeds is very small, they have an obvious effect on balancing or strengthening feed nutrition, improving feed quality, and improving the quality of animal products. In actual production, during the transition period, that is, during the process of larval and juvenile fish switching from live bait to artificial compound feeds, one or more animal health products, such as vitamin premixes, probiotics, etc., are usually added to the compound feeds. Their role is to supplement the lack of nutrition and can also improve the health level of larval and juvenile fish during the transition period.

[0006] However, during the initial feeding stage of larvae and juveniles, how to improve their direct ingestion of artificial compound feed requires further exploration. On the other hand, existing research has shown that it is indeed possible to improve the growth rate and survival rate of larvae and juveniles by feeding them nutritionally fortified live baits. For example, feeding Artemia nauplii fortified with eicosapentaenoic acid and docosahexaenoic acid. Moreover, studies have also found that different nutritionally fortified baits have different effects on the growth and survival of fish. For example, Du Tao et al. (2010) conducted a nutritionally fortified larval rearing experiment on Lates calcarifer, Trachinotus ovatus, and Sciaenops ocellatus using yeast rotifers and rotifers fortified with Chlorella vulgaris and Spirulina platensis. The results showed that the survival rate of larvae and juveniles was significantly higher in the group fed rotifers fortified with Chlorella vulgaris and Spirulina powder than in the yeast group. However, most of the research focuses on the nutritional fortification of live baits, and further research and development are still needed on how to nutritionally fortify artificial feed for the initial feeding of larvae and juveniles. Qin Zhiqing et al. (2020) reared 5-day-old larvae of Acrossocheilius hemispinus that had just started feeding in glass tanks measuring 60 cm × 50 cm × 50 cm at a density of 300 fish per tank, and fed them freshwater rotifers (10 ind. / mL), earthworm slurry (passed through a 150 μm sieve), egg yolk (washed by kneading through a 250 μm gauze), fry starter feed, and shrimp milk powder. After a 22-day culture experiment, it was found that freshwater rotifers were the most suitable initial feeding bait for A. hemispinus larvae; earthworm slurry was a suitable initial feeding bait and could be used as a substitute for A. hemispinus larvae when freshwater rotifers were lacking, indicating that current artificial baits cannot fully meet the growth requirements of larvae and juveniles. Therefore, it is necessary to develop a nutritional fortifier for fortified larvae and juveniles' initial feeding feed to facilitate the direct use of feed for larvae and juveniles to start feeding and improve the growth and survival rate of larvae and juveniles. Summary of the Invention

[0007] In view of the characteristics of larvae and juveniles, such as small body size, weak motility, poor ability to adapt to the external environment, and underdeveloped digestive systems, the present invention provides a nutritional fortifier that can promote larvae and juveniles to directly ingest artificial compound feed during the initial feeding stage and significantly improve the growth and survival rate of larvae and juveniles. The components of the nutritional fortifier include eicosapentaenoic acid, docosahexaenoic acid, arachidonic acid, protease, lipase, amylase, vitamin C, lecithin, taurine, lysine, etc.

[0008] Another object of the present invention is to provide the application of the above-mentioned nutritional fortifier as an additive for larvae and juveniles' initial feeding feed.

[0009] To achieve the above object, the present invention is realized through the following technical solutions:

[0010] A nutritional fortifier for the first-feeding feed of juvenile fish, which is composed of the following components by weight: 2-8 parts of eicosapentaenoic acid, 4-16 parts of docosahexaenoic acid, 0.1-1 part of arachidonic acid, 4-12 parts of compound enzyme preparation, 2-10 parts of vitamin C, 40-120 parts of lecithin, 7-15 parts of taurine, and 15-25 parts of lysine.

[0011] Each part of the compound enzyme preparation contains 10,000-30,000 U of protease, 8,000-15,000 U of lipase, and 10,000-30,000 U of amylase.

[0012] In the above-mentioned scheme, preferably, 3-6 parts of eicosapentaenoic acid, 6-10 parts of docosahexaenoic acid, 0.3-0.7 part of arachidonic acid, 5-10 parts of compound enzyme preparation, 4-8 parts of vitamin C, 70-90 parts of lecithin, 10-12 parts of taurine, and 15-18 parts of lysine.

[0013] The protection scope of the present invention also includes: the application of the above nutritional fortifier in the preparation of the first-feeding feed additive for juvenile fish; the additive can improve the body length, body weight and survival rate of juvenile fish.

[0014] In the above-mentioned application, preferably, the juvenile fish is juvenile sturgeon.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The present invention provides a nutritional fortifier for the first-feeding feed of juvenile fish and its application. The raw materials of the feed additive provided by the present invention are easily available, and the production process is simple. It can promote the juvenile fish to directly ingest the feed during the first-feeding period, further improve the digestion ability of the juvenile fish, effectively supplement the demand of the juvenile fish for exogenous nutrients, improve the growth of the juvenile fish, increase the immunity and improve the survival rate. Description of the Drawings

[0017] Figure 1 Schematic diagram of the body length change of juvenile sturgeon fed with different first-feeding feeds.

[0018] Figure 2 Schematic diagram of the body weight change of juvenile sturgeon fed with different first-feeding feeds.

[0019] Figure 3 Schematic diagram of the survival rate of juvenile sturgeon.

[0020] Figure 4 Schematic diagram of the body length change of juvenile largemouth bass fed with different first-feeding feeds.

[0021] Figure 5 Schematic diagram of the body weight change of juvenile largemouth bass fed with different first-feeding feeds.

[0022] Figure 6It is a schematic diagram of the survival rate of Micropterus salmoides larvae and juveniles.

[0023] Figure 7 It is a schematic diagram of the body length change of Pelteobagrus fulvidraco larvae and juveniles fed with different initial feeds.

[0024] Figure 8 It is a schematic diagram of the weight change of Pelteobagrus fulvidraco larvae and juveniles fed with different initial feeds.

[0025] Figure 9 It is a schematic diagram of the survival rate of Pelteobagrus fulvidraco larvae and juveniles.

[0026] Figure 10 It is a schematic diagram of the body length change of Acipenser larvae and juveniles fed with different initial feeds.

[0027] Figure 11 It is a schematic diagram of the weight change of Acipenser larvae and juveniles fed with different initial feeds.

[0028] Figure 12 It is a schematic diagram of the survival rate of Acipenser larvae and juveniles. Specific implementation manners

[0029] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited by the embodiments. The technical solutions described in the present invention are all conventional solutions in the art unless otherwise specified. The reagents or materials described in the present invention are all from commercial channels unless otherwise specified.

[0030] In the embodiments of the present invention, each portion of the compound enzyme preparation contains 20000 U of protease, 10000 U of lipase, and 20000 U of amylase.

[0031] Example 1:

[0032] A feed additive for strengthening the nutrition of larvae and juveniles is composed of the following components in parts by weight: 3 parts of eicosapentaenoic acid, 6 parts of docosahexaenoic acid, 0.3 part of arachidonic acid, 5 parts of compound enzyme preparation, 4 parts of vitamin C, 70 parts of lecithin, 10 parts of taurine, and 15 parts of lysine, and can be uniformly mixed by a conventional method.

[0033] Example 2:

[0034] A feed additive for strengthening the nutrition of larvae and juveniles is composed of the following components in parts by weight: 4 parts of eicosapentaenoic acid, 8 parts of docosahexaenoic acid, 0.5 part of arachidonic acid, 7 parts of compound enzyme preparation, 6 parts of vitamin C, 80 parts of lecithin, 11 parts of taurine, and 16 parts of lysine, and can be uniformly mixed by a conventional method.

[0035] Example 3:

[0036] A feed additive for strengthening the nutrition of juvenile fish is composed of the following components by weight: 6 parts of eicosapentaenoic acid, 10 parts of docosahexaenoic acid, 0.7 part of eicosatetraenoic acid, 10 parts of compound enzyme preparation, 8 parts of vitamin C, 90 parts of lecithin, 12 parts of taurine, and 18 parts of lysine. It can be mixed evenly by conventional methods.

[0037] Example 4:

[0038] Application of the nutritional fortifier for the initial feed of juvenile fish in the feed for juvenile sturgeon:

[0039] 1. Test feed

[0040] There are 4 kinds of feeds, namely tubifex worms (the most commonly used biological feed for cultivating juvenile sturgeon), a certain brand of sturgeon initial feed (referred to as Brand A, common in the market), Brand A sturgeon initial feed added with 1% by weight of Example 1, and Brand A sturgeon initial feed added with 1.2% by weight of Example 2.

[0041] 2. Test fish and aquaculture system

[0042] The 6-day-old juvenile sturgeon used in the test is the most important hybrid sturgeon (Acipenser baerii♀×A. schrenckii♂) for aquaculture in China, sourced from a professional sturgeon breeding farm in Beijing.

[0043] The test is carried out in 12 circular aquaculture barrels with running water. The water source is groundwater, the water temperature is 18.9 - 20.2°C, pH is 7.1 - 8.0, and DO≥9mg / L. The diameter of the aquaculture barrel is 1.5m and the water depth is 40cm. 1000 juvenile fish are stocked in each barrel.

[0044] 3. Test management

[0045] After the 6-day-old hybrid sturgeon fry enter the system, a small number of seedlings start to cluster at the bottom. At 7 days old, the fry have clustered, part of the yolk has been absorbed, and they start to excrete feces. Therefore, the daily feeding amount starts at 60% of the body weight, and after 10 days old, the daily feeding amount is 30 - 40% of the body weight, and after 15 days old, it is 20 - 30% of the body weight. Feed is given 6 times a day, with an interval of 4h each time. The tubifex worms are ground into a slurry by a meat grinder and splashed evenly throughout the barrel, and the feed is mixed with water and splashed evenly throughout the barrel for each meal.

[0046] 4. Test indicators

[0047] Measurement of body length and body weight: Randomly select 30 representative fry every 5 days, measure the body length with a vernier caliper, and measure the body weight of the fry with a thousandth balance.

[0048] Survival rate (%) = [(number of fish at the start of the test - number of fish at the end of the test) / number of fish at the start of the test] × 100%

[0049] 5. Experimental Results

[0050] 5.1 Effects of Different Initial Feeds on the Body Length of Juvenile and Larval Sturgeon

[0051] As Figure 1 can be seen, during the 25-day breeding period, the juvenile and larval sturgeons fed with different feeds all had varying degrees of body length growth. The body length of the juvenile and larval sturgeons fed with tubifex worms increased the most. Among the three groups fed with feeds, there was no significant difference in the first 15 days, but at 20 days, the body length growth of the juvenile and larval sturgeons fed with the feeds of Example 1 and Example 2 was better than that fed with Brand A, indicating that the application of the additives of Example 1 and Example 2 is more conducive to the increase in the body length of juvenile and larval sturgeons.

[0052] 5.2 Effects of Different Initial Feeds on the Body Weight of Juvenile and Larval Sturgeon

[0053] As Figure 2 can be seen, tubifex worms are most beneficial to the body weight growth of juvenile and larval sturgeons. Compared with the feed of Brand A, the feeds of Example 1 and Example 2 are more conducive to the body weight growth of juvenile and larval sturgeons, indicating that the application of the additives of Example 1 and Example 2 is more conducive to the body weight growth of juvenile and larval sturgeons.

[0054] 5.3 Effects of Different Initial Feeds on the Survival Rate of Juvenile and Larval Sturgeon

[0055] As Figure 3 can be seen, feeding the feed containing the additives of Example 1 and Example 2 can make the survival rate of juvenile and larval sturgeons reach a similar effect to that of feeding tubifex worms, and is significantly higher than that of only feeding the feed of Brand A. It shows that the application of the additives of Example 1 and Example 2 is more conducive to the survival of juvenile and larval sturgeons.

[0056] Example 5:

[0057] Application of the Nutritional Fortifier for the Initial Feed of Juvenile and Larval Fish in the Feed of Micropterus salmoides Larvae and Juveniles

[0058] 1. Test Feeds

[0059] Four kinds of feeds, namely bloodworms (the most commonly used biological feed for culturing Micropterus salmoides larvae and juveniles, collected from ponds through a fine mesh), the initial feed for Micropterus salmoides larvae and juveniles of a certain brand (abbreviated as Brand B, commonly seen in the market), the initial feed for Micropterus salmoides larvae and juveniles of Brand B added with 0.8% by weight of Example 2, and the initial feed for Micropterus salmoides larvae and juveniles of Brand B added with 1.5% by weight of Example 3.

[0060] 2. Test Fish and Culturing System

[0061] The experiment selected 4-day-old Micropterus salmoides larvae and juveniles, which were sourced from a large-scale fry farm of Micropterus salmoides in Guangdong. The experiment was conducted in 12 circular culture barrels with recirculating water. The water temperature was 23.5 - 25.5 °C, pH was 6.8 - 7.2, and DO ≥ 5 mg / L. The diameter of the culture barrel was 1.2 m and the water depth was 80 cm. 1500 larvae and juveniles were stocked in each barrel. The culture system used shaded fluorescent lamps as the light source, with a light cycle of 12:12 (day:night) and a light intensity of approximately 400 Lux.

[0062] 3. Experimental management

[0063] The experimental feed was fed to the Micropterus salmoides larvae and juveniles starting from the second day after they were placed in the recirculating water culture system. Before each feeding, clapping hands was done to facilitate the formation of conditioned reflexes in the experimental fish. The fish were fed 4 times a day, with an interval of 6 hours each time. The red worms were directly poured into the culture barrel, and the feed was mixed with water and evenly sprinkled throughout the barrel for each meal. The feeding rate was the same as in Example 4.

[0064] 4. Experimental indicators

[0065] Measurement of body length and weight: At 5 days, 10 days, 20 days, and 30 days after feeding, 30 representative fry were randomly selected for the experiment. The body length was measured with a vernier caliper, and the weight of the fry was measured with a thousandth balance.

[0066] Survival rate (%) = [(Number of fish at the start of the experiment - Number of fish at the end of the experiment) / Number of fish at the start of the experiment] × 100%

[0067] 5. Experimental results

[0068] 5.1 Effect of different initial feeds on the body length of Micropterus salmoides larvae and juveniles

[0069] As Figure 4 can be seen, red worms are most beneficial for the body length growth of Micropterus salmoides larvae and juveniles. However, compared with the initial feed of Brand B, adding Example 2 and Example 3 can improve the body length growth of the larvae and juveniles.

[0070] 5.2 Effect of different initial feeds on the weight of Micropterus salmoides larvae and juveniles

[0071] As Figure 5 can be seen, red worms are most beneficial for the weight growth of Micropterus salmoides larvae and juveniles. However, compared with the initial feed of Brand B, adding Example 2 and Example 3 can improve the weight increase of the larvae and juveniles.

[0072] 5.3 Effect of different initial feeds on the survival rate of Micropterus salmoides larvae and juveniles

[0073] As Figure 5 can be seen, the survival rate of Micropterus salmoides larvae and juveniles fed with red worms is the highest. However, compared with the initial feed of Brand B, adding Example 2 and Example 3 can improve the survival rate of the larvae and juveniles.

[0074] Example 6:

[0075] Application of nutritional fortifier for larval and juvenile fish starter feed in Pelteobagrus fulvidraco larval and juvenile fish feed:

[0076] 1. Test feeds

[0077] There are 4 kinds of feeds, namely bloodworms (the most commonly used biological feed for cultivating Pelteobagrus fulvidraco larval and juvenile fish, collected from ponds through a fine mesh), a certain brand of Pelteobagrus fulvidraco larval and juvenile fish starter feed (abbreviated as Brand C, common in the market), Brand C Pelteobagrus fulvidraco larval and juvenile fish starter feed added with 1.0% by weight of Example 1, and Brand C Pelteobagrus fulvidraco larval and juvenile fish starter feed added with 0.9% by weight of Example 3.

[0078] 2. Test fish and culture system

[0079] The test uses 2-day-old Pelteobagrus fulvidraco larval and juvenile fish, sourced from a large-scale Pelteobagrus fulvidraco fry farm in Hubei. The test is carried out in 12 circular culture barrels with recirculating water. The water temperature is 27.0 - 29.0 °C, pH is 6.5 - 7.5, and DO ≥ 5 mg / L. The diameter of the culture barrel is 1.2 m and the water depth is 80 cm. 1000 larval and juvenile fish are stocked in each barrel. The culture system uses shaded fluorescent lamps as the light source, with a light cycle of 12:12 for day:night and a light intensity of about 400 Lux.

[0080] 3. Test management

[0081] After the Pelteobagrus fulvidraco larval and juvenile fish are put into the recirculating water culture system, feeding with the experimental feed starts on the 2nd day. Clap hands before each feed to facilitate the formation of conditioned reflexes in the test fish. The bloodworms are directly poured into the culture barrel, and the feed is mixed with water and splashed evenly throughout the barrel for each meal. The feeding rate is the same as in Example 4.

[0082] 4. Test indicators

[0083] Measurement of body length and body weight: During the test, 30 representative fry are randomly selected at 5d, 10d, 15d, and 25d after feeding. The body length is measured with a vernier caliper, and the body weight of the fry is measured with a thousandth balance.

[0084] Survival rate (%) = [(number of fish tails at the start of the test – number of fish tails at the end of the test) / number of fish tails at the start of the test] × 100%

[0085] 5. Experimental results

[0086] 5.1 Effect of different starter feeds on the body length of Pelteobagrus fulvidraco larval and juvenile fish

[0087] It can be seen from Figure 7 that feeding bloodworms is most beneficial to the growth of the body length of Pelteobagrus fulvidraco larval and juvenile fish. Compared with feeding Brand C feed, feeding the feeds added with Example 1 and Example 3 increased the body length growth of the larval and juvenile fish.

[0088] 5.2 Effects of Different Initial Feeds on the Body Weight of Larval and Juvenile Pelteobagrus fulvidraco

[0089] It can be seen from Figure 8 that feeding Tubifex is most beneficial to the increase of the body weight of Pelteobagrus fulvidraco. Compared with feeding the feed of Brand C, adding Example 1 and Example 3 to the feed is more beneficial to the increase of the body weight of larval and juvenile Pelteobagrus fulvidraco.

[0090] 5.3 Effects of Different Initial Feeds on the Survival Rate of Larval and Juvenile Pelteobagrus fulvidraco

[0091] It can be seen from Figure 9 that the survival rate of larval and juvenile Pelteobagrus fulvidraco fed with Tubifex is the highest. Compared with feeding the feed of Brand C, the survival rate of larval and juvenile Pelteobagrus fulvidraco fed with the feed containing Example 1 and Example 3 is higher.

[0092] Example 7:

[0093] Different Nutritional Fortifiers are Used in the Feed for Larval and Juvenile Sturgeon

[0094] By comparing the survival rates of Example 4, Example 5 and Example 6, it can be known that in the applications of sturgeon, Pelteobagrus fulvidraco and Micropterus salmoides, the application effect of the nutritional fortifier in the initial feed for larval and juvenile fish is better in the feed for larval and juvenile sturgeon. Further compare the promotion effects of the nutritional fortifier in the initial feed for larval and juvenile fish of the present invention and the mixtures that can be used as fortifiers in larval and juvenile sturgeon:

[0095] 1. Test Feeds

[0096] 5 kinds of feeds, namely Tubifex (the most commonly used biological feed for cultivating larval and juvenile sturgeon), a certain brand of sturgeon initial feed (abbreviated as Brand A, common in the market), Brand A sturgeon initial feed added with 1.2% by weight of Example 1, Brand A sturgeon initial feed added with 1.2% by weight of Comparative Example 1, Brand A sturgeon initial feed added with 1.2% by weight of Comparative Example 2, and Brand A sturgeon initial feed added with Comparative Example 3 according to the published literature respectively.

[0097] The components of Comparative Example 1 are as follows, by weight, 3 parts of eicosapentaenoic acid, 7 parts of docosahexaenoic acid, 0.2 part of arachidonic acid, and 55 parts of phospholipids, and they are mixed evenly by the conventional method.

[0098] The components of Comparative Example 2 are as follows, by weight, consisting of the following components by weight: 8 parts of eicosapentaenoic acid, 8 parts of docosahexaenoic acid, 8 parts of arachidonic acid, 20 parts of complex enzyme preparation, 15 parts of vitamin C, 100 parts of lecithin, 20 parts of taurine, and 30 parts of lysine, and they are mixed evenly by the conventional method.

[0099] The additive amounts of various components in each kilogram of the starting feed for juvenile and larval A brand sturgeon are as follows: eicosapentaenoic acid 1.87 g (Luo, 2019), docosahexaenoic acid 0.8 g (Luo, 2019), arachidonic acid 0.023 g (Luo, 2019), protease 225 U (Ghodrati, 2021), lipase 6000 U (Ran, 2015), amylase 3457 U (Hlophe, 2016), vitamin C 300 mg (Gao Qiang, 2006), lecithin 60 g (Fatemeh, 2018), taurine 1 g (Hoseini, 2018), lysine 30 g (Foshtomi, 2016).

[0100] 2. Test fish and culture system

[0101] The test used 6-day-old juvenile and larval sturgeon, the most important cultured hybrid sturgeon in China (Acipenser baerii♀×A. schrenckii♂), sourced from a professional sturgeon breeding farm in Beijing.

[0102] The test was conducted in 18 circular culture barrels with running water. The water source was groundwater, with a water temperature of 18.9 - 20.2°C, pH 7.1 - 8.0, and DO ≥ 9 mg / L. The diameter of the culture barrels was 1.5 m and the water depth was 40 cm. 1000 juvenile and larval fish were stocked in each barrel.

[0103] 3. Test management

[0104] Same as Example 4.

[0105] 4. Test indicators

[0106] Same as Example 4.

[0107] 5. Experimental results

[0108] 5.1 Effect of different starting feeds on the body length of juvenile and larval sturgeon

[0109] It can be seen from Figure 10 that feeding Tubifex worms is most beneficial to the growth of the body length of juvenile and larval sturgeon. Compared with feeding the A brand feed, feeding the feeds added with Example 2 and Comparative Example 3 promoted the increase in body length, but Comparative Example 2 was significantly higher than Comparative Example 3.

[0110] 5.2 Effect of different starting feeds on the body weight of juvenile and larval sturgeon

[0111] It can be seen from Figure 11 that feeding Tubifex worms is most beneficial to the increase in the body weight of sturgeon. Adding Example 2 to the feed can achieve a body weight similar to that of feeding Tubifex worms. Compared with feeding the A brand feed, the body weights of Comparative Example 1 and Comparative Example 2 decreased slightly, and that of Comparative Example 3 increased, but it was far less than that of Example 2.

[0112] 5.3 Effects of Different Starter Feeds on the Survival Rate of Juvenile and Larval Sturgeon

[0113] It can be seen from Figure 12 that the survival rate of juvenile and larval sturgeon fed with tubifex worms is the highest, and adding Example 2 to the feed can achieve a survival rate similar to that of feeding tubifex worms. However, feeding Comparative Example 1, Comparative Example 2, and Comparative Example 3 did not achieve a similar survival rate.

[0114] From the comparison of the above results, it can be seen that the feed additive of the present invention can effectively improve the survival rate of juvenile and larval fish, improve growth, and further effectively reduce the application of live bait.

[0115] The above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, etc. within the scope of the present invention, and all belong to the scope of protection of the present invention.

Claims

1. Application of a nutritional fortifier in the preparation of an additive for the first-feeding feed of larvae and juvenile fish, characterized in that, the nutritional fortifier is composed of the following components in parts by weight: 2-8 parts of eicosapentaenoic acid, 4-16 parts of docosahexaenoic acid, 0.1-1 part of arachidonic acid, 4-12 parts of compound enzyme preparation, 2-10 parts of vitamin C, 40-120 parts of lecithin, 7-15 parts of taurine, 15-25 parts of lysine; wherein, each part of the compound enzyme preparation contains 10,000-30,000 U of protease, 8,000-15,000 U of lipase, and 10,000-30,000 U of amylase.

2. The application according to claim 1, characterized in that: 3-6 parts of eicosapentaenoic acid, 6-10 parts of docosahexaenoic acid, 0.3-0.7 part of arachidonic acid, 5-10 parts of compound enzyme preparation, 4-8 parts of vitamin C, 70-90 parts of lecithin, 10-12 parts of taurine, 15-18 parts of lysine.

3. The application according to claim 1, wherein the additive improves the body length, body weight and survival rate of larvae and juvenile fish.

4. The application according to claim 1, wherein the larvae and juvenile fish are larvae and juvenile sturgeons.

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